Referring to FIG. 1 and FIG. 2, the structure and operation of a human eye are described as context for the present invention. FIG. 1 and FIG. 2 are cross section views of an anterior part of a human eye 10 having a visual axis VA for near vision and distance vision, respectively, in an axial plane of the human body. The human eye 10 has an anterior transparent cap like structure known as a cornea 11 connected at its circumferential periphery to a spherical exterior body made of tough connective tissue known as sclera 12 at an annular corneal limbus 13. An iris 14 inwardly extends into the human eye 10 from its root 16 at the corneal limbus 13 to divide the human eye's anterior part into an anterior chamber 17 and a posterior chamber 18. The iris 14 is a thin annular muscle structure with a central pupil. The iris 14 is activated by inter alia ambient light conditions, focusing for near vision, and other factors for a consequential change in pupil diameter. An annular ciliary body 19 is connected to zonular fibers 21 which in turn are peripherally connected to an equatorial edge of a capsular bag 22 having an anterior capsule 23 and a posterior capsule 24 and containing a natural crystalline lens 26. Contraction of the ciliary body 19 allows the lens 26 to thicken to its natural thickness T1 along the visual axis VA for greater positive optical power for near vision (see FIG. 1). Relaxation of the ciliary body 19 tensions the zonular fibers 21 which draws the capsular bag 22 radially outward as shown by arrows A for compressing the lens 26 to shorten its thickness along the visual axis VA to T2<T1 for lower positive optical power for distance vision (see FIG. 2). Near vision is defined at a distance range of between about 33 cm to 40 cm and requires an additional positive optical power of between about 3 Diopter to 2.5 Diopter over best corrected distance vision. Healthy human eyes undergo pupillary miosis to about 2 mm pupil diameter for near vision from an about 3 mm to 6 mm pupil diameter for distance vision corresponding to ambient illumination conditions.
Cataract surgery involves capsulorhexis in an anterior capsule 23 for enabling removal of a natural crystalline lens 26. Capsulorhexis typically involves preparing an about 4 mm to about 5 mm diameter circular aperture in an anterior capsule 23 to leave an annular anterior capsule flange 27 and an intact posterior capsule 24. FIG. 1 and FIG. 2 denote the boundary of the circular aperture by arrows B. Separation between a capsular bag's annular anterior capsule flange 27 and its intact posterior capsule 24 enables growth of capsular epithelial cells which naturally migrate over its internal capsule surfaces inducing opacification of a posterior capsule 24 abbreviated as PCO and/or capsular fibrosis with capsular contraction. While secondary cataracts are ruptured by YAG laser to clear a visual axis and restore vision, capsular contraction is untreatable.
Accommodating Intraocular Lens (AIOL) assemblages designed to be positioned within a vacated capsular bag 22 are known as in-the-bag AIOL assemblages. Presently envisaged in-the-bag AIOL assemblages are large monolithic dual optics structures of inherent bulkiness that require a large corneal incision for implantation in a human eye and proper positioning inside its capsular bag since a slight deviation of one optics of a dual optics structure from its visual axis results in optical distortion. Moreover, previously envisaged in-the-bag AIOL assemblages do not lend to being formed with a toric lens component for correcting astigmatism since dialing a bulky dual optics structure inside a capsular bag to a predetermined angle required to correct astigmatism poses a great risk of tearing a capsular bag.
There is a need for improved in-the-bag AIOL assemblages.